The invention relates to a method for activation of temperature time monitors, and temperature time monitors operating therewith, according to the precharacterizing portion of claim 1.
Perishable products, such as medications, vaccines, stored blood, but also food products, have already been monitored with various chemical or electronic monitors for a long time. This is done especially by recording and analyzing time/temperature data and indicating if certain threshold values are being exceeded.
In the case of a monitor that includes a registering or integrating function, it is important that the precise start time is selectable. Various methods for a starting or activating, respectively, of the monitor and its function, respectively, have already been applied up to now:                by push button or switch (Q-tag, Tag Alert, Coolwatch, etc.)        by plug-type contacts (Spyco)        by infrared signal        by RF signal (Schreiner labels)        by removal of an insulating strip (Freezeye).        
All of these methods are relatively involved and/or they have reliability problems.